Device for producing water on board of an airplane

ABSTRACT

A device for producing water on board an aircraft includes at least one high temperature fuel cell entirely or partially integrated into a combustion chamber arrangement of a gas turbine aircraft engine. The combination of at least one fuel cell and a gas turbine engine is adapted to operate exclusively with hydrogen and atmospheric oxygen, and is embodied in an aircraft propulsion engine and/or an auxiliary power unit used for producing compressed air for a cabin and a power supply of the aircraft. The at least one high temperature fuel cell is fed with pure hydrogen on an anode side and with air on a cathode side. The combustion chambers of the turbine engine are fed with an air-hydrogen mixture, whereby at least the hydrogen supply can be regulated or completely shut off.

FIELD OF THE INVENTION

The invention relates to an apparatus for producing water on board of anaircraft while using one or more fuel cells, wherein a partial orcomplete integration of a water production unit in the form of one ormore high temperature fuel cells into an aircraft engine is provided insuch a manner that the combustion chambers of the aircraft engine arereplaced completely or partially by the high temperature fuel cells andthus either supplementing or completely replacing the process that takesplace in the conventional type combustion chambers.

BACKGROUND INFORMATION

European Patent Publication EP 957,026 A2 discloses an energy supplyunit on board of an aircraft for substituting a main propulsion plant,an auxiliary power unit, a ram air turbine or a nickel cadmium (NiCd)battery. A fuel cell serves for producing d.c. current whereby exhaustair of the aircraft air-conditioning plant or external air of theaircraft are used as air supply for the fuel cell. Water is recoveredfrom the fuel cell exhaust air for the water supply of the aircraft.Subsequently the fuel cell exhaust air is discharged to the aircraftsurroundings. This also applies to the hydrogen emanating from the fuelcell. A water production is performed by a condenser arranged in theaircraft outlet.

European Patent Publication EP 967,676 A1 describes a jet engine havingfuel cells integrated into the combustion chambers, wherein the fuelcells are arranged on the combustion chambers, contrary to the teachingof the new main claim as seen from the enclosure, wherein the combustionchambers are partially or completely replaced by the high temperaturefuel cell or cells. In the prior, known propulsion plant the process ofthe propulsion plant is merely used for the operation of the fuel cell.

SUMMARY OF THE INVENTION

Thus, it is the object of the invention to provide an apparatus of thetype mentioned above in which a fuel cells gas turbine combination isprovided for the exclusive operation with hydrogen and air oxygen, as apropulsion plant and/or as auxiliary power unit for the water andpressurized air supply of the cabin and for current generation.

This object has been achieved according to the invention in that thehigh temperature fuel cells are constructed as the type: solid oxidefuel cell (SOFC) or molten carbonate fuel cell (MCFC), or are of a typecomparable in power and temperature level; that pure hydrogen issupplied to the anode side of said high temperature fuel cells, that airis supplied to the cathode side of the high temperature fuel cells, thata mixture of hydrogen and air is supplied to the combustion chambers,that at least the hydrogen supply is constructed for a closed loopcontrol or can be shut off completely, and that a single stage ormultistage turbine is connected downstream of the anode side of the hightemperature fuel cell, said turbine converting the thermal energy of theanode exhaust gas into rotation energy.

Embodiments of the invention are described in the dependent claims 2 to24.

It is provided to thereby replace at least one, preferably however,several combustion chambers by one or more high temperature fuel cells.In distinction to the mentioned subject matter at least one or morecombustion chambers are retained for combusting a hydrogen watermixture. The combustion chambers and the high temperature fuel cells arepreferably arranged in alternating succession as a ring shape around theshaft or shafts of the gas turbine.

The combustion chambers serve for starting the gas turbine and the hightemperature fuel cells and for temporarily increasing the air throughputof the gas turbine e.g. for the start of an aircraft. During continuousoperation, exclusively the thermal energy of the high temperature fuelcell is used for generating the air throughput. The water generationtakes place at the anode side i.e. at the hydrogen side of the hightemperature fuel cell. This so called anode exhaust gas consists of 100%water steam (superheated steam) when the supplied hydrogen is completelytransformed. This superheated steam is fed through a turbine where thesteam is cooled by expansion whereby thermal energy is converted intorotation energy of the turbine shaft. This rotational energy is used ina compressor for generating the pre-pressure that is required at thehydrogen side for the high temperature fuel cell.

The water vapor is eventually condensed out in a further process stageto obtain pure H₂O, that is, distilled water. This water is supplied tothe different consumers or to a salination unit to produce drinkingwater. Gray water becoming available is collected in a collectingcontainer in the same way as the water proportion discharged whendehydrating black water. The water quantities are evaporated in anevaporator operated by the heat available from the water condensationprocess and supplied together with the steam proportion from the anodeexhaust gas of the high temperature fuel cell, not needed for watergeneration, to the second turbine stage of the gas turbine. On the airside a so-called fan sucks-in external air and/or cabin exhaust air.During normal operation this fan is driven by the second turbine stage,during starting by an electric motor. The air passing through the fan isfirst compressed by a compressor arranged downstream, and is thenfurther compressed in a further compressor for the combustion chambersand for the air side of the high temperature fuel cell. The thermalenergy introduced through the combustion chambers or the hightemperature fuel cell first drives the first turbine stage and,following the above described introduction of gray water into the hotexhaust air flow, the second turbine stage. The number of the compressorand turbine stages, as well as the number of the combustion chambers andof the high temperature fuel cells can be varied as desired depending onthe requirements with regard to different types.

The advantages of the apparatus according to the invention reside in thefollowing:

-   -   a) flexibility with regard to short duration power demands,    -   b) high integration of the individual process steps,    -   c) high purity of the generated water,    -   d) high system efficiency and    -   e) a weight reduction.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described in connection with an exampleembodiment, with reference to the accompanying drawing, of which thesingle figure schematically shows a block diagram of the exampleembodiment of an inventive apparatus for producing water on board anaircraft.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT OF THE INVENTION

The drawing illustrates an example embodiment according to theinvention.

The single FIGURE shows a water generation system including a tank forliquid hydrogen.

Thus, a use in a so-called “cryoplane” is particularly advantageous. Ascan be seen in the drawing, a high temperature fuel cell 7 replacespartially a combustion chamber 7A of an aircraft propulsion plant 2.Pure hydrogen is supplied to the anode side and air is supplied to thecathode side of the high temperature fuel cell 7, while a mixture ofhydrogen and air is supplied to the combustion chamber 7A, whereby atleast the hydrogen supply is constructed to be controllable in closedloop fashion or to be completely shut-off. A single stage or multistageturbine 16 is connected downstream to the anode side of the hightemperature fuel cell 7. The turbine 16 converts the thermal energy ofthe anode exhaust gas 35 into rotation energy. Fuel cells of the typesolid oxide fuel cell (SOFC) or molten carbonate fuel cell (MCFC) or ofa type comparable with regard to power and temperature may be used.

A condensation process 18 is connected downstream of the hightemperature fuel cell 7. The process 18 condenses water out of a portionof the anode exhaust gas 35 of the fuel cell 7. Further, the hightemperature fuel cell 7 may be pressurized on both sides, on the onehand, on the air or oxygen side and on the fuel or hydrogen side, on theother hand, whereby equal or even unequal pressures are permissible onthe anode side and on the cathode side. Using liquid or gaseous hydrogenis possible. Liquid hydrogen 1 can be evaporated prior to entering thehigh temperature fuel cell 7 or the combustion chamber 7A, whereby theevaporator 17 may be operated with the process heat of the anode exhaustgas condenser 18. A special embodiment of the apparatus according to theinvention is characterized in that the evaporator 17 is arranged in aring shape around the condenser 18 or circularly inside the condenser 18whereby the evaporator is constructed as a pipe bundle heat exchanger.In this case also at least a portion of the condensation process 18 canbe operated with cooling air 19.

It is possible to collect used water as well as not needed condensate ina container 32. The air 20 that was heated in the condensation process18 is advantageously used for evaporating the gray water in a separatecontainer 33 into which the gray water is fed by a pump 45, whereby afilter is provided for retaining solid and suspended materials. Waterhaving a distilled quality is taken from the condensation process 18 viaa drinking water tank 22, and is distributed in such a manner thatgalleys 23, hand wash basins 24 and the showers 25 receive drinkingwater that has been generated by adding a dose of salt in a salinationunit 43, while toilets 27 and the air humidification 26 are suppliedwith distilled water. The turbine stages 8, 9 can drive the compressorstages 5, 6 as well as the fan 11, whereby the compressor stages 5, 6pressurize the air side of the high temperature fuel cell 7 and of thecombustion chamber 7A. The air throughput 3 of the fan 11 can be usedeither for propulsion in an engine or in an APU for pressurizing thecompressed air systems and/or of the air conditioning. For this purposerespectively one fan 11 is coupled with a first compressor stage 5 and asecond turbine stage 9, and a second compressor stage 6 and a firstturbine stage 8, that that run on coaxial shafts one within the otherand at different revolutions per minute. The number of coaxial shaftsrunning one within the other is constructed as desired.

The waste water is collected in a collection tank 28, which has aseparator/blower 29 connected to an outlet thereof, and the waste wateris then completely or partially dehydrated in a dehydration unit 30connected to an outlet of the tank 28 through a pump 44. The waterproportion thus gained is fed to the gray water collection tank 32 fromwhich it is pumped by a pump 45 to the gray water evaporator 33. Wastewater is discharged at 31 from the tank 28. It is of special advantage:

-   -   that the apparatus can also be operated without dispensing water        to a water system,    -   that the combustion chambers and the high temperature fuel cells        can be operated separately and in any desired combination with        one another; and    -   that in a separate operation of combustion chambers or high        temperature fuel cells 7 individual combustion chambers or high        temperature fuel cells can be switched off.

Further as shown in the single drawing figure, the inventive apparatusmay additionally have the following features. The high temperature fuelcell 7 can provide a direct current output 4. An output of the graywater evaporator 33 can provide a gray water injection 10 into the lowpressure turbine stage 9. Air 21 can also be output from the gray waterevaporator 33. The turbine 16 can drive a hydrogen compressor 13 thatprovides a flow of compressed hydrogen 15 to the fuel cell 7, and can becoupled via a belt drive 37 with a starter 12 that is coupled to the fan11 for starting the propulsion plant 2. Hydrogen 14 can be provided tothe hydrogen compressor 13 from the hydrogen evaporator 17. Water steam34 from the turbine 16 can be fed to the condenser 18 and the gray waterevaporator 33. Exhaust air or steam 36 can be emitted from the lowpressure turbine stage 9.

1. An apparatus for producing water on board of an aircraft while usingone or more fuel cells, comprising at least one high temperature fuelcell that has an anode side and a cathode side and that is integratedinto a heat-producing arrangement of an aircraft engine, wherein theheat-producing arrangement optionally additionally includes at least onecombustion chamber, wherein the high temperature fuel cell is adapted tocarry out a fuel cell process and the optional combustion chamber isadapted to carry out a combustion process, characterized in that: thehigh temperature fuel cell is an oxide ceramic fuel cell (SOFC - solidoxide fuel cell), or a molten carbonate fuel cell (MCFC), or a fuel cellthat has a power and temperature level equivalent to an oxide ceramicfuel cell or a molten carbonate fuel cell; the apparatus includes ahydrogen supply that comprises a source of liquid or gaseous hydrogenand that is arranged and adapted to supply pure hydrogen to the anodeside of said high temperature fuel cell; an air intake is arranged andadapted to supply air to the cathode side of said high temperature fuelcell; the hydrogen supply and the air intake are further arranged andadapted to supply a mixture of hydrogen and air to the combustionchamber; at least the hydrogen supply is constructed for a closed loopcontrol or can be shut off completely; the apparatus further includes aliquid hydrogen evaporator positioned upstream of the high temperaturefuel cell or the combustion chamber; and the apparatus further includesa single stage or multistage turbine (16) connected downstream of theanode side of the high temperature fuel cell, said turbine adapted toconvert thermal energy of anode exhaust gas (35) into rotation energy.2. The apparatus of claim 1, characterized in that the conversion of thethermal energy takes place by a Stirling motor and/or by one or morecombinations of different thermal engines, for example a turbine and aStirling motor.
 3. The apparatus of claim 1, comprising a compressor(13) and means for supplying gained mechanical energy to saidcompressor.
 4. The apparatus of claim 3, wherein said compressor is usedfor charging said anode side of said high temperature fuel cell (7) withhydrogen (15) under pressure.
 5. The apparatus of claim 1, furthercomprising a condensation process (18) connected downstream of said hightemperature fuel cell or high temperature fuel cells (7), saidcondensation process condensing water out of a portion of anode exhaustgas (35) of said fuel cell (7).
 6. The apparatus of claim 1, whereinsaid high temperature fuel cell is constructed for pressurizing the airor oxygen side, and the fuel or hydrogen side, whereby equal ordifferent pressures are permissible on the anode side and on the cathodeside.
 7. The apparatus of claim 1, further comprising an anode exhaustgas condenser (18) and wherein said evaporator (17) is constructed to beoperable by process heat of said anode exhaust gas condenser (18). 8.The apparatus of claim 7, wherein said evaporator (17) is constructed asa pipe bundle heat exchanger which is arranged as a ring shape aroundsaid condenser (18) or circularly within said condenser (18).
 9. Theapparatus of claim 7, wherein at least a portion of said condenser (18)is operable with cooling air (19).
 10. The apparatus of claim 1, whereinproduced steam is blown in upstream of a second turbine stage (9) ofsaid multistage turbine where said steam is mixed with cathode exhaustair.
 11. The apparatus of claim 5, further comprising means forwithdrawing water of distilled quality from the condensation process(18) and for distributing said distilled quality water, a salinationstation (43) for adding a dose of salt to produce drinking water forgalleys, hand wash basins and showers and for supplying distilled waterto toilets and humidifiers.
 12. The apparatus of claim 1, wherein saidmultistage turbine comprises turbine stages (8, 9) for drivingcompressor stages (5, 6) and a fan (11), and wherein the compressorstages (5, 6) pressurize an air side of said high temperature fuel cell(7) and of said combustion chamber (7A).
 13. The apparatus of claim 12,wherein an air throughput (3) of said fan (11) is used either in anengine for propulsion or in an APU for pressurization of pressurized airsystems and/or of an air conditioning system.
 14. The apparatus of claim12, wherein said fan (11) is coupled with a first compressor stage (6)and with the second turbine stage (9), and wherein a second compressorstage (6) and the first turbine stage (8) are coupled with each otherand run on coaxial shafts with different revolutions per minutes. 15.The apparatus of claim 14, wherein the number of coupled compressorstages and turbine stages, the direction of rotation of these stages,and the number of coaxial shafts rotating one within the other areconstructed at discretion.
 16. The apparatus of claim 1, constructed forbeing operable without supplying water to a water system.
 17. Theapparatus of claim 1, wherein said at least one combustion chamber andsaid at least one high temperature fuel cell are operable separately andin any desired combination.
 18. The apparatus of claim 1, whereinindividual combustion chambers or high temperature fuel cells areadapted to be switched off for a separate operation of combustionchambers or high temperature fuel cells.
 19. An apparatus for producingwater on board of an aircraft while using one or more fuel cells,comprising at least one high temperature fuel cell that has an anodeside and a cathode side and that is integrated into a heat-producingarrangement of an aircraft engine, wherein the heat-producingarrangement optionally additionally includes at least one combustionchamber, wherein the high temperature fuel cell is adapted to carry outa fuel cell process and the optional combustion chamber is adapted tocarry out a combustion process, characterized in that: the hightemperature fuel cell is an oxide ceramic fuel cell (SOFC - solid oxidefuel cell), or a molten carbonate fuel cell (MCFC), or a fuel cell thathas a power and temperature level equivalent to an oxide ceramic fuelcell or a molten carbonate fuel cell; the apparatus includes a hydrogensupply that is arranged and adapted to supply pure hydrogen to the anodeside of said high temperature fuel cell; an air intake is arranged andadapted to supply air to the cathode side of said high temperature fuelcell; the hydrogen supply and the air intake are further arranged andadapted to supply a mixture of hydrogen and air to the combustionchamber; at least the hydrogen supply is constructed for a closed loopcontrol or can be shut off completely; the apparatus further includes asingle stage or multistage turbine (16) connected downstream of theanode side of the high temperature fuel cell, said turbine adapted toconvert thermal energy of anode exhaust gas (35) into rotation energy;and the apparatus further includes a gray water evaporator (33) arrangedand adapted so that air (20) heated in a condensation process is usedfor evaporating gray water in said gray water evaporator, a pump (45)arranged for feeding said gray water into said gray water evaporator(33), and a filter arranged for retaining solid and suspended matter outof said gray water.
 20. The apparatus of claim 19, further comprising agray water collection tank (32) for collecting used water and unneededcondensate as the gray water.
 21. The apparatus of claim 20, furthercomprising a waste water collection tank (28) adapted to collect wastewater, and a dehydrator (30) adapted to completely or partiallydehydrate said waste water and a thus-gained water portion is fed intothe gray water collection tank (32).
 22. The apparatus of claim 19,wherein any germs and microorganisms present in the gray water (32) arethermally killed.